The invention concerns a safety device for a high-pressure connector of a hydraulic device, in particular a hydraulic screw tensioning device.
U.S. 2008/034925 A1 discloses a screw tensioning device comprised of a hydraulic cylinder that is supported on a machine part that is to be tightened by means of a threaded bolt and a nut. Arranged therein is a seal-tightly guided piston that together with the cylinder forms an annular chamber that is supported on an extension of a change sleeve that is screwed onto a thread of the threaded bolt. A further component of the device is a controlled pressure medium supply to the annular chamber.
Such a screw tensioning device enables that a precisely predetermined purely axial pretensioning force is applied to a screw in order to tighten or release the nut that is screwed onto the screw. For this purpose, a change sleeve of the screw tightening device is screwed onto the thread projecting upwardly past the nut and subsequently the screw tensioning device is pressurized with hydraulic pressure. This has the result that the screw is tensioned purely by axial lengthening. The tensile forces that are applied onto the screw are extremely high so that the screw tensioning device and its individual parts are greatly stressed because the hydraulic pressures can be up to 4,000 bar.
DE 100 35 691 A1 discloses a high-pressure hose conduit for connecting a high-pressure pump to a hydraulic screw connecting device that is secured against throwing off parts of the high-pressure hose conduit upon breakage of these parts. For this purpose, the high-pressure hose conduit is provided with a press-in nipple that is pressed into it and comprises a cylindrical area and a conical area that widens toward an area of the press-in nipple projecting from the high-pressure hose; moreover, grooves on the exterior side of the areas; moreover, a press-in sleeve that effects the pressure-tight connection between the high-pressure hose and the press-in nipple, that spans both, and that extends across the length of the areas but is press-fit on the high-pressure hose only in the conical area; and an elongate safety sleeve that is attached at least by friction connection to the area of the press-in nipple projecting from the high-pressure hose and from the press-in sleeve and to the exterior side of the press-in sleeve. This screw tensioning device and the high-pressure hose conduit that is employed therein have proven successful in practice but it has been found that in individual cases in the area of the high-pressure connector on the hydraulic device leaks may occur. The hydraulic fluid that escapes in this context at high pressure may represent a risk of injury for operating personnel in the vicinity.